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Post by soop on Sept 14, 2018 10:14:39 GMT
This is a future project I haven't yet started. I picked up a Sony boombox with a broken tape deck, and I intend to wire some shit together to make it a Bluetooth speaker, ala Evan Kale: www.youtube.com/watch?v=5iIcGaf7qPAThis is something I've been meaning to do for a couple of years now. the boombox has two inputs, radio and tape (obviously I don't need the tape part). I'm figuring that I'll leave the radio part in and have the other option be Bluetooth, though since that's also "off", I'll need to figure out a power switch. I think I'd also like to have an aux jack. I have considered just wiring in an audio Chromecast, which is a lot better in some respects, but the downside is that I don't currently use any audio streaming apps and I don't want to pay for a subscription. Then there's this Bluetooth amp I've just seen, which kind of has everything I need in one package If anybody has any input on this, I'm all ears.
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Post by ClodBuster on Sept 14, 2018 10:51:41 GMT
Soop, this reminds me of what The Post Apocalyptic Inventor did:
I've got a twenty years old Aiwa boombox in the kitchen. Since it is in need for repair, due to a dodgy headphone port interrupting the speakers connection, I want to give it a similar treatment.
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Post by soop on Sept 14, 2018 11:33:28 GMT
Nice! Thanks for the links, I'll have a watch
*edit* these are really good so far, thanks for the hook-up. I think these are much better for my project. It's definitely more hacky though, and I don't like the idea of adding switches to the front, that's quite ugly.
But I know a lot more now than I did.
My tape deck is broken anyway which is why mine was so cheap, so Im definitely going to repurpose the tape input, but I can probably also repurpose the tape buttons. I'm considering whether to have the line-in too. I could repurpose the headphone jack, but it would be nice to have the jack intelligently switch from bluetooth to line-in if something is connected. I think I can do that...t
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Post by soop on Nov 17, 2018 17:04:45 GMT
Well, I put everything together and it all works great. I have a passthrough for the aux socket so that it bypasses bluetooth when a cable is plugged in the only bad thing is that it's a bit quiet over bluetooth.
Not sure if it's the bluetooth reciever tbh, but I've put some feelers out.
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Post by ClodBuster on Nov 18, 2018 11:26:38 GMT
Good job on your modding work! Soop, does the source device for your Bluetooth receiver allow for volume changes when being connected?
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Post by soop on Nov 18, 2018 15:01:17 GMT
Good job on your modding work! Soop, does the source device for your Bluetooth receiver allow for volume changes when being connected? It does. I've looked at a few things, such as putting my phone into developer mode and overriding some of the Bluetooth settings, but it's still a bit iffy. The best thing I've managed so far is to remove the connector for the tape head driver, which makes it listenable. I think I might have to bypass the tape pcb entirely, since it adds a lot of fuzz, but I'm not 100% what I need from it to make the amp select the tape (if it's removed completely, everything goes through the radio selector) Those guys on tapeheads.net were really helpful btw. And that lamp younsuggested - found one on amazon for £12 on sale, and it's perfect!h
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Post by ClodBuster on Nov 18, 2018 20:11:59 GMT
I'm glad they were helpful, I got my tapedeck fixed thanks to them, too.
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Post by soop on Feb 21, 2019 15:26:34 GMT
I need to get back on this. The problem I was facing last time was that the sound from the Bluetooth module was far too quiet. I even got another one in case it was a fault with the module. Then I went towards getting a Bluetooth amplifier, which would bypass the internal amp, and in fact kind of defeat the point. Actually, I have another idea. I should have plugged it into the aux jack before I disassembled it and soldered it. That's a typical thing for me to do.
Well I guess that's the plan for tonight, see if the Bluetooth sound is quiet through the aux jack
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Post by soop on Feb 24, 2019 14:10:41 GMT
Hmm. I tested the Bluetooth receiver itself through the headphone jack. Same problem. I think I was unfortunate to get two duff recievers
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Post by dshadoff on Feb 24, 2019 14:15:24 GMT
Have you tried using a preamp ?
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Post by soop on Feb 24, 2019 18:31:44 GMT
Have you tried using a preamp ? I *think* there's a preamp built into the boombox itself. It'sbeen a while since I looked at the datasheets, but there's a chip in there which I think is a preamp. I did actually buy a separate bluetooth amplifier, but that would then replace most of the original hardwaree, and lose some functionality, which I'm leaning against. do you have something specific in mind that might help?
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Post by dshadoff on Feb 24, 2019 20:38:01 GMT
...Just that the symptoms you describe (level too low) would usually be one of two things: either an impedance mismatch (i.e. amplifier demanding more power from input than the input can provide), or a problem with peak-to-peak voltage levels.
Yes, a preamp is usually inside these things, and it's usually to take "microphone" levels up to "auxiliary" levels... but it's not clear whether you're feeding into its inputs (or whether it's still healthy).
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Post by soop on Feb 25, 2019 9:43:41 GMT
...Just that the symptoms you describe (level too low) would usually be one of two things: either an impedance mismatch (i.e. amplifier demanding more power from input than the input can provide), or a problem with peak-to-peak voltage levels. Yes, a preamp is usually inside these things, and it's usually to take "microphone" levels up to "auxiliary" levels... but it's not clear whether you're feeding into its inputs (or whether it's still healthy). Yeah, there's a jack wired directly to the preamp. Normal line source works fine through the same jack, so it's something to do with the Bluetooth module, I'm confident of that. The first part you mention sounds like a possibility. It currently uses it's own lithium ion battery, but I did have it hooked up to 5v, through it's micro USB input.
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Post by soop on Feb 28, 2019 10:56:28 GMT
Got a new receiver which works MUCH better. However there is some distortion with the sound at high volumes. There's a VERY noticeable thrum when using the AC, but that's not going to be a factor in the final build. I suspect it's due to the cables running past the AC transformer, and I plan on re-routing the wires once everything works.
I might eventually do a re-cap as well to see if that improves sound quality.
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Post by SignOfZeta on Mar 2, 2019 16:01:40 GMT
I hate to be discouraging but...those cheap d-class amps on Amazon with the BT built in will sound way way better than this old POS jam box with paper drivers a 2 watt amplifier and you’ve already done more work trying to intigrate convenience than one spends in a life time of just plugging in a cable that works every time.
In summary:
Nostalgia sucks, at least when you measure power levels and total harmonic distortion.
Bluetooth consumes vastly more time than it saves in many cases.
I would just buy the entire d class amp and build that into the little blaster. Replace the speakers with...anything new that fits.
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